Phosphorus is a well-known culprit for water quality problems in Wisconsin, and an excess of this nutrient in soils impedes efforts to clean up lakes. Several groups of people play critical roles in reducing phosphorus pollution and improving lakes – farmers, policymakers and scientists, to name a few – but how does the "average" person fit in?

Phosphorus is one of the most important components in the ongoing struggle to balance agricultural prosperity with water quality. What scientists call "legacy phosphorus" — or "legacy P," a common abbreviation — exists in a sort of nutrient limbo.

Phosphorus has always been a big part of just about any water-quality discussion, including those about its levels in the Great Lakes. It also intersects with another big ecological problem in the lakes: invasive species.